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Abstract

The complete molecule of the title compound, C22H16N2O4, is generated by a crystallographic centre of inversion. The plane of the central aromatic ring is tilted by 11.85 (4)° with respect to the outer aromatic ring. The crystal packing is determined by van der Waals inter­actions, with stair-like stacking between adjacent aromatic rings. The stacks are staggered and each layer is approximately 3.8 Å from the next. The closest inter­molecular contact (approximately 2.42 Å) is between an O atom and a vinyl H atom.

Acknowledgments

This work was supported in part by Research Development Grants from the Pennsylvania State University. The author also acknowledges Benjamin E. Kucera, Victor G. Young Jr, and the X-Ray Crystallographic Laboratory at the University of Minnesota.

supplementary crystallographic
information

Comment

Distyrylbenzene derivatives have been studied as laser dyes, components of
organic light-emitting diodes, and as model compounds for the study of
conductivity and molecular properties in substituted
p-phenylenevinylene (PPV) polymers. For background information on
photonic materials, see: He et al. (2008). For related systems
of
stilbene, see: Moreno-Fuquen et al. (2008, 2009). For
literature
related to the synthesis, see: Borsche (1912).

Experimental

Synthesis was carried out following literature procedures (Nakatsuj) by standard
Wittig synthesis. To a mixture of p-phenylenedimethylene-
bis(tripheny1phosphonium chloride) (1.00 g, 1.43 mmol) and
p-nitrobenzaldehyde (0.432 g 2.86 mmol) in EtOH (10 ml) was added 0.2 mol/L EtOLi(20 ml, 4.0 mmol) and the mixture was stirred overnight. The
resulting reaction mixture was poured into water to give a yellow precipitate
(0.4 g, 75%) which was filtered off, washed with EtOH, dried under reduced
pressure, m.p. 289–290. Crystallization attempts from various solvents
yielded only powders. Yellowish orange crystals however were grown by
sublimation.

Refinement

All hydrogen atoms were placed in ideal positions and refined as riding atoms
with relative isotropic displacement parameters.

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The threshold expression of F2 >
σ(F2) is used only for calculating R-factors(gt) etc.
and is not relevant to the choice of reflections for refinement.
R-factors based on F2 are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger.